Effective antiviral therapy of two murine leukemias with an interferon‐inducing synthetic carboxylate copolymer

A synthetic anionic copolymer was employed to induce interferon in vivo. The ability of the induced interferon to protect mice inoculated with lethal doses of Friend or Rauscher leukemia virus was examined. Four parameters were employed to assess the antiviral activity of the induced interferon; inhibition of splenomegaly; viral‐induced spleen foci; viral replication; and increase in survival time. Daily treatment with a low dose of copolymer was more effective than a single treatment with a high dose. A higher percentage of treated mice was completely protected from a lethal dose of Friend or Rauscher leukemia virus when compared with the controls. A relationship occurred between the effect of copolymer‐induced interferon and the infecting dose of leukemia virus. Protection developed only when treatment was initiated prior to virus challenge.